You mean the ones that decrease the cooldown on missed attacks (Black Heart and Mew's Guts)? You would have to test it in-game to be sure, but short of that, the general rule is that everything stacks unless explicitly stated otherwise. Since it doesn't say anywhere in the add-on descriptions, or on the Gamepedia wiki, that they don't stack, it's probably safe to assume that they do. If not, that's an oversight on the part of the UI designers.
Tldr: This is an archived version of the DBD forum, it has all posts, comments and media. The archived data will be published at the end of October. This site is not in any way affiliated with or endorsed by Behaviour Interactive.
Comments
You mean the ones that decrease the cooldown on missed attacks (Black Heart and Mew's Guts)? You would have to test it in-game to be sure, but short of that, the general rule is that everything stacks unless explicitly stated otherwise. Since it doesn't say anywhere in the add-on descriptions, or on the Gamepedia wiki, that they don't stack, it's probably safe to assume that they do. If not, that's an oversight on the part of the UI designers.